文思湖底泥COD释放规律模拟研究

采用室内模拟实验方法,研究环境因子（温度、pH、扰动强度、供气量）对底泥释放COD的影响。结果表明,水温升高能加速底泥中有机质的释放;上覆水在弱酸至中性条件下底泥释放有机质最低;扰动上覆水体会加快有机质的释放。     

铁还原菌作用下含镉聚合硫酸铁絮体中铁还原与镉释放规律及其影响因素

选取Shewanella oneidensis MR-1为供试铁还原菌,旨在研究MR-1在还原含Cd聚合硫酸铁絮体过程中,絮体中Fe（Ⅲ）还原、Cd释放规律及影响因素。结果表明,扰动可促进絮体中Fe（Ⅲ）还原及Cd释放;絮体中Cd的添加使得Fe（Ⅲ）还原过程中产生的二次矿物主要物相由磁铁矿转变为针铁矿,且Cd浓度的增加导致Fe（Ⅲ）还原率逐渐降低,Cd释放率也逐渐降低;絮体中Fe浓度的逐渐增大同样使得Fe（Ⅲ）还原率逐渐降低,Cd释放率则先增大后减小;腐殖质类模型物质蒽醌-2,6-二磺酸钠的添加可提高絮体中Fe（Ⅲ）的还原率,进而促进Cd的释放。对同一体系或不同体系间的Fe（Ⅲ）还原率及Cd释放率进行线性拟合,结果发现较大的Fe（Ⅲ）还原率能够导致絮体中Cd的更多释放,从而对环境造成更大的危害。     

不同温度下西安汉城湖沉积物吸附、释放特性和磷形态

以西安汉城湖为研究对象,2015年4月对湖体沉积物进行现场调查和采样分析,共设4个采样点,研究不同温度下沉积物磷的吸附释放特性及沉积物磷形态的分布。结果表明,沉积物磷等温吸附随着温度的升高而增大,吸附特征符合修正的Langmuir模型,最大吸附容量Qmax的范围为507.21~786.77 mg·kg-1。磷动力学吸附主要发生在实验进行前12 h之内,吸附量基本达到或超过72 h吸附平衡时吸附总量的85%。磷动力学释放量范围为2.02~11.058 mg·kg-1,且在6 h达到最大值。沉积物总磷的含量范围为655.37~1.809.38 mg·kg-1,以无机磷为主,沉积物不同形态磷含量为TP > IP > HCl-P > OP > NaOH-P。沉积物富营养化风险指数ERI的范围为5.92~11.86,在10℃和20℃时,4个采样点的ERI均在10以下,属于低风险,在30℃时,4个采样点的ERI均在10以上,属于中等富营养化风险。     

湖泊底泥磷释放及磷形态变化

为研究底泥中内源性磷释放对城市景观水体富营养化的影响,以西安市曲江南湖为对象,采用底泥磷形态标准测试方法(SMT)分析了磷的赋存形态,通过模拟实验探究了在不同环境条件(温度、pH和溶解氧)下磷形态变化的特征。结果表明:温度升高促进内源磷的释放,在夏季加剧水体富营养化程度;碱性条件有利于磷的释放,增大补给水源可减少底泥释磷量;厌氧环境下底泥释磷量是好氧时的3.96倍;Al-P 和Ca-P较稳定,在酸性条件下会加速其溶解;NH4+-P、 Fe-P 和OrgP受溶解氧、pH和温度影响较大,其吸附与释放能力有明显的差异。     

过硫酸盐缓释材料释放过程模型构建

为预测评估过硫酸盐缓释材料的释放性能,对释放过程模型的构建以及模型的验证进行了研究。借助微积分思想,从材料体的概化分割、初始条件设定、每个小单元的状态标定、各个小单元中过硫酸钾的迁移变化量以及材料最外层释放过硫酸盐的量5个方面构建过硫酸盐缓释材料释放模型,利用Excel-VBA编程实现其释放过程模拟。采用欧盟标准NEN7375测试过硫酸盐缓释材料释放性能并获得模型参数。通过输入相关模型参数得到过硫酸盐动态迁移过程及其释放特征曲线,并利用实测数据与模拟数据进行拟合校验。结果表明,模型模拟值与实测值拟合较好,平均误差为1.88%,表明该模型设计合理,能够准确模拟过硫酸盐缓释材料释放过程,可作为缓释材料优化设计工具。     

Development of controlled release formulations of azadirachtin-A employing poly(ethylene glycol) based amphiphilic copolymers

Controlled release (CR) formulations of azadirachtin-A, a bioactive constituent derived from the seed of Azadirachta indica A. Juss (Meliaceae), have been prepared using commercially available polyvinyl chloride, polyethylene glycol (PEG) and laboratory synthesized poly ethylene glycol–based amphiphilic copolymers. Copolymers of polyethylene glycol and various dimethyl esters, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of azadirachtin-A, release in water from the different formulations was studied. Release from the commercial polyethylene glycol (PEG) formulation was faster than the other CR formulations. The rate of release of encapsulated azadirachtin-A from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of azadirachtin-A, in water ranged from 0.47 to 1.18 in the tested formulations. The release was diffusion controlled with a half release time (t_1/2) of 3.05 to 42.80 days in water from different matrices. The results suggest that depending upon the polymer matrix used, the application rate of azadirachtin-A can be optimized to achieve insect control at the desired level and period.     

Accidental release: Fuzzy selection of adequate formal model

Risk assessment of a chemical process plant requires the application of a variety of consequence models in order to estimate the potential physical effects of accidental releases. The types of models required vary depending upon the substance under consideration and the circumstances of a release. The objective of this study was the development and application of a system based upon ‘fuzzy logic’, for the selection of a computer model to be used in consequence analysis in specific situations where only certain types of consequence models can be used. The collection of data for modelling purposes from different kinds of computer model and application of fuzzy methods were also important aims of the study.     

沉水植被对河流温室气体释放减缓作用研究

为揭示沉水植物生态修复在减缓河流温室气体释放方面的作用,在浙江省嘉善县选择盛家湾（有沉水植物）和东龙港（无沉水植物）2条河流,利用扩散模型法对其水体CO₂、CH₄、N₂O释放通量进行24 h连续监测,并进行对比分析。结果表明：2条河流除盛家湾水体在16:00表现为CO₂吸收外,其余监测时间内3种气体均呈过饱和状态,表现为向大气释放温室气体,24 h内比较,有沉水植物的盛家湾可减少89%的温室气体释放。将气体释放通量与环境因子进行相关性分析发现,盛家湾水体CO₂释放通量与水温、pH、溶解氧浓度呈显著负相关,与氧化还原电位呈显著正相关,N₂O释放通量与水温、pH、溶解氧浓度呈显著正相关,与氧化还原电位呈显著负相关;东龙港水体CO₂释放通量与水温呈显著正相关,CH₄释放通量与水温、溶解氧浓度呈显著正相关,N₂O释放通量与水温呈显著正相关。

     

原位洗脱技术对凉水河底泥中氮、磷释放特征的影响

为探讨新兴底泥原位修复技术—原位洗脱技术对城市河流凉水河底泥中氮、磷释放的抑制作用,于现场采集洗脱前后样品并设计室内静态模拟实验,分析了实验期间洗脱组和对照组上覆水中${{\rm{NH}}_4^ + }$-N、${{\rm{NO}}_3^ - }$-N、TN、${{\rm{PO}}_4^{3 - }}$-P、TP浓度和释放速率变化特征。结果表明：洗脱组释放第30天时,${{\rm{NH}}_4^ + }$-N由底泥向上覆水中平均释放速率(−6.51±0.32) mg·(m²·d)⁻¹,对应上覆水中${{\rm{NH}}_4^ + }$-N平均浓度为0.52 mg·L⁻¹,较对照组下降了89.4%;${{\rm{PO}}_4^{3 - }}$-P和TP平均释放速率较对照组降低了78.1%和83.0%,上覆水中TP平均浓度为0.22 mg·L⁻¹,较对照组下降了68.1%。原位洗脱技术对底泥中${{\rm{NH}}_4^ +} $-N、${{\rm{PO}}_4^{3 - }}$-P释放的抑制作用主要通过对有机氮、磷物质的削减和水-沉积物界面还原环境的改善来实现。     

The Influence of Anthropogenic Contamination On Metals Release From Coastal Sediment Suspensions with Aerated Sea Water

The zinc, cadmium, copper and lead release from the uncontaminated and contaminated coastal sediments with aerated sea water was studied. the metals transfer to the dissolved forms was monitored during one-two months by differential pulse anodic voltammetry (DPASV). the sediments with different initial degree of contamination were sampled in the Peter the Great Bay, Sea of Japan around Vladivostok-the biggest city in Russian Far East. Sediment contamination by metals led to increased release to solution of zinc due to sulphide oxidation and cadmium on account of organic matter decomposition. the copper behaviour was complicated by strong binding with organic matter and enhancements of copper release can only be seen in sediment with a low organic matter content. Significant lead transfer to dissolved forms was not observed regardless of sediment contamination. the temperature affected the release of cadmium and copper through enhanced organic matter destruction. the dissolved metal fluxes from the sediment transformation are compared with metal fluxes towards bottom. Such comparisons show that second contamination by dissolved metals of the studied coastal environment may be important for cadmium only.